Remaining deaf to UN and US calls to open dialogue, the Sudanese president Omar al Bashir has hardened his stance against its southern neighbor. "With [them], we deal with guns and bullets," he said Monday.

On the same time, Southern Sudan has accused Khartoum of bombing its territory again, killing two, a claim Sudan has denied.

"No negotiations with these people," said Mr. Bashir during his visit to Heglig, which was recaptured from South Sudan.

"With them, we are negotiating with guns and bullets," he said, three days after he announced that his forces had driven the army of Southern Sudan out of Heglig. Southern Sudan, for its part spoke about a voluntary withdrawal, under international pressure.

On Monday, the president of the United States Barack Obama further stated that "the killings of innocent (should) stop," calling Khartoum and Juba to "have the courage" to negotiate an end to violence.

Secretary General Ban Ki-moon on his part "condemned the aerial bombardment of southern Sudan" by Khartoum forces and urged the Sudanese government "to cease immediately all hostilities". He also encouraged the presidents of Sudan and Southern Sudan, Omar al-Bashir and Salva Kiir, "to resume dialogue urgently".

After two weeks of heavy fighting, the oil-rich Heglig area was strewn with corpses of South Sudan soldiers. The valuable oil infrastructure in the area, which accounts for half of the production in the North, was badly damaged, according to eyewitnesses.

"The death toll is 1,200 for the SPLM," the former southern rebels movement, which is now in power in South Sudan, said the commander of the Sudanese army, Kamal Marouf, in front of some 2,000 soldiers. He has however not disclosed the death toll of his army.